答复

1. GBA Editor
   马丁·霍洛拉|Feb 03, 2010 04:58am|#1

   凯伦，
   If you spend more money to heat your house during the winter than you do to cool the house during the summer — as most Americans do — then you're better off with a dark-colored roof, not a "cool roof." The only exception would be if you made the mistake of putting HVAC equipment and ductwork in your attic. (I hope you didn't make this mistake.)

   如果您的阁楼里有管道，如果您有空调，则需要浅色凉爽屋顶。您还应该考虑一系列补救措施来解决阁楼的静物问题。

   凉爽的屋顶是电动实用高管的宠物，因为酷屋顶有助于公用事业地址达到峰值负荷问题。这就是为什么公用事业高管经常有运动，以鼓励凉爽的屋顶，即使在供暖气候中也是如此。公用事业管理人员希望在炎热的夏季下午较小的峰值负荷。凉爽的屋顶帮助 - 但每年都在冬季增加房主的加热负荷，房主是净失败者。

2. 
   Doug McEvers|2010年2月3日09:06 AM|#2

   优秀的马丁，我有一个朋友告诉我，他正在考虑在丹佛西部的山上办公楼的凉爽屋顶!!!!一些销售人员有他的耳朵，我出去了，为建筑物进行了快速的能源使用分析，发现它缺乏一些领域。凉爽的屋顶将帮助原因完全没有，这座建筑实际上具有适当的改造不需要AC系统，可能只是夜间吹扫凉爽的空气。

   凯伦，
   建筑物性能以非常谨慎的设计，超越代码（双），非常密闭（1ACH50）或更少，基于位置的适当窗口选择，尺寸和放置，非常谨慎的设计。在Critera满意之后，您可以精细调整以利用被动和其他方法。

3. 
   凯伦·雷|Feb 03, 2010 09:35am|#3

   所以你不需要考虑到夏天的阳光直接闪耀的更长时间？我谈到的建筑科学专家之一说，即使为明尼苏达州仍然推荐一个白色的屋顶，因为它在夏季提供的福利仍将超过冬季黑暗屋顶。
   I would think that this decision can't just be made on whether you spend more on heating and cooling because the effects of the summer and winter sun can't be split 50/50.

4. GBA Editor
   马丁·霍洛拉|Feb 03, 2010 10:12am|#4

   凯伦，
   你是对你的问题的准确，详细的答案取决于许多变量，所以没有简单的答案。你已经做出了一个重要的观点 - 太阳角（以及每天的太阳小时数）从冬天变为夏天。影响计算的其他要点：
   1.为了冬天的百分比是你的南屋顶覆盖着雪？
   2.您的屋顶平面绝缘，还是位于您的阁楼底板上的绝缘？
   3. What is the R-value of your ceiling insulation?

   These calculations get complicated fast.

   Here's a takeaway point: the better your thermal envelope, the more irrelevant the cool-roof-versus-warm-room question becomes. If you have a tight envelope and thick insulation, it really doesn't matter.

5. 
   Riversong|Feb 03, 2010 07:13pm|#5

   凯伦，

   As Martin suggested, there are far too many variables to answer that question in general. it can, however, be answered for a specific site and a specific house design.

   Relevant variables include: site topography, natural (or other) shading, percent cloudy days during each season, height of house, orientation of house, angle of roof, type and mass of roofing, limit of thermal boundary (ceiling or roof), whether the roof is vented or not (and how well).

   Minimizing East and West window area may be more important to prevent overheating in the winter than in the summer, depending on latitude. Remember that it is at the equinoxes (swing or shoulder seasons) that the sun rises and sets in the East and West. In summer, it can rise 30° or more to the South of East and will be about 50° high in the sky by the time it's due East. In the winter, the sun rises 30° or so North of East and remains low in the sky all day, shining more directly into windows.

   As others have stated, cool roofs are important for hot, sunny climates and ventilating those roofs also helps except in the most humid marine climates. But a cooler color of asphalt composition shingles will provide more longevity to the roof anywhere. Dark asphalt roofing shrinks and cracks from over-absorption of radiant solar heat.

6. 
   Riversong|2010年2月3日07:15 PM|#6

   Edit (when are we going to get an edit function?):

   My post should read: Summer sun rises North of East and winter sun rises South of East .